The NADPH-supported rates of formation of two species of active oxygen, superoxide (02-) and peroxide (H202) by hepatic microsomes, will be determined and attempts will be made to learn the routes from which these arise. Substrates of three of the electron transfer oxidative pathways, the lipid peroxidase, the mixed function oxidase, and the fatty acyl CoA delta 9 desaturase will be provided to assess changes in the rates and patterns of active oxygen release during oxidative metabolism. Total microsome NADPH:02 stoichiometry and stoichiometries with substrates at specific pathways will be examined to confirm our earlier observation that operation of each pathway is independent of the operation of the other, despite the fact that they use the same electron input enzymes. Inhibitors of the pathways will be used to isolate and measure NADPH:02:product stoichiometry of each pathway. Antibody studies will also be performed to trace the source of active oxygen released during microsomal consumption of NADPH. Adrenochrome formation by microsomes will be examined to learn the catalytic active oxygen specie for the reaction, and the use of various chemical quenching agents is planned to examine this and the other oxidative reactions.